How shape/material of speaker footers impact their effectivness

[Fitzcaraldo215]

I see the references to science here and there, but I also question the relevance. Speed of sound in different materials? Why would that matter? I do not see any references to how any of these devices change the sound measurably in the room or to their provable audibility via bias-controlled tests. I view it as much ado about nothing worth pursuing.

I myself do believe speakers should be firmly placed on the floor. For my large, heavy main speakers, I just use common, hardware store, screw-in furniture glides with about a 1.5" smooth steel mushroom on the end together with a lock nut on the shaft. They have been sitting firmly in the same now deeply compressed spots on my carpet for years. They do not rock, vibrate or move any more than they would if on their provided spikes, which I do not use. In the absence of evidence to the contrary, that is good enough for me.

I do have smaller surround speakers on heavy stands. I did remove the speaker spikes and bolted them tightly to the stands. The stands also sit in their own, now deep impressions firmly in the carpet.

 

[fas42]

I don't have the foggiest, but it would seem safer to say yes than to say no as a material without would probably be impossible.

Not really. In everyday items it's called memory foam, the stuff when you squash it just slooowly reverts back to normal shape. With furniture foam you can buy the standard, just springy, varieties; or specify memory versions, for a bit more cost.

The technical term is viscoelastic, means exactly what it implies: springy but also viscous; the shape reverts back slowly, rather than as fast as possible. Sorbothane is the classic commercial brand that people think of.

The big advantage is that viscous means damping - the energy stored by any deflection is converted to heat, rather than decaying very slowly - continual bouncing is prevented. The suspension of a car is a perfect example; with worn out shock absorbers, dampers you can see the wheels doing a merry dance.

 

[fas42]

Problem is that the stand is not infinitely stiff and has its own natural frequencies. Make the connection to the floor as solid as you like.

Not infinitely stiff, but can be made vastly superior to a simple metal pedestal - I would suggest that optimal mounting of speakers is not common.

 

[cjf]

Please tell me about the differences between the metals cited and what practical relevance that would have in this application. What practical difference between 6 and say 4km/s in a material a few mm thick?

The way I see it the relevance here would be the fact that vibration energy does indeed behave differently (as proven by the hundreds or thousands of documents found online written by real scientists/engineers who study this kind of stuff) depending on what solid material the vibration encounters in its travels to wherever its going. In this case that destination would be the surface the speaker is resting on and what material/object it used as a medium to get to that point.

If you want audio related examples that would require delving into the dreaded subjective opinions of what folks hear who have tried different footers under their speaker and report hearing a change after doing so.

As far as how the thickness of the material plays into all of this there are measurements available in the inch/sec range that are more applicable to this topic so its not all about Kilometers/Miles. A quick and dirty example of a thin material having an effect on vibration would be something like the various "tape/films" available from 3M and its probable that the Sorbothane linked earlier also has thin films available. All these can be measured in the .xxx mm range of thickness. With that said I feel confident that a few mm can make a big difference in all this.

One interesting article I found on devices known as "Thickness Gauges" talks about how different materials and their internal makeup/structure can affect sound/vibration propagation:

http://www.olympus-ims.com/en/ndt-theory/thickness-gage/factors/

http://www.olympus-ims.com/en/appli...ry-ultrasonics/introduction-thickness-gaging/

If your not aware of what these devices do, they use transducers to generate sound at various Freq and use that to measure the thickness of a material by calculating the time it takes for the sound to reflect back into the gauge. There is a decent explanation on the challenges involved in doing this due to the material makeup of different metals,plastics..etc.

 

[cjf]

Just found an interesting article on "what spikes do!" - http://www.audioholics.com/loudspeaker-design/speaker-spikes-and-cones-2013-what2019s-the-point. I agree with much of the material in that ... overall, my mantra is stability, stability, stability.

So it seems they are saying that one of the main purposes of the Spike is to increase the Mass of the cabinet so that it is less likely to move Fore/Aft in the same directions that the speaker cones travel. With that in mind I still wonder if my original thought of placing the Spike into a small 1" cube made from hardened tool steel or tungsten carbide that has a Hole thru its center big enough to accept at least half the length of the Spike to increase the amount of "beef" that is in contact with the cube and then place the whole assembly on top of something like the Symposium Svelte Shelfs would function well as a stable,energy absorbing platform.

I guess the theory would be that the Svelte Shelf would absorb enough of the energy as to not result in the speaker rocking/moving back and forth despite the surfaces involved being fairly smooth. Granted the Mass of the speaker would decrease in the vertical due to the larger contact patch the spike/cube would have but the hope would then be for the Svelte shelf to do its job to absorb whats being transmitted thru the feet.

 

[cjf]

Here's a pic for clarity purposes of the factory spike, outrigger setup and Herbie cups deployed under my speakers as they sit today

 

[March Audio]

The way I see it the relevance here would be the fact that vibration energy does indeed behave differently (as proven by the hundreds or thousands of documents found online written by real scientists/engineers who study this kind of stuff) depending on what solid material the vibration encounters in its travels to wherever its going. In this case that destination would be the surface the speaker is resting on and what material/object it used as a medium to get to that point.

If you want audio related examples that would require delving into the dreaded subjective opinions of what folks hear who have tried different footers under their speaker and report hearing a change after doing so.

As far as how the thickness of the material plays into all of this there are measurements available in the inch/sec range that are more applicable to this topic so its not all about Kilometers/Miles. A quick and dirty example of a thin material having an effect on vibration would be something like the various "tape/films" available from 3M and its probable that the Sorbothane linked earlier also has thin films available. All these can be measured in the .xxx mm range of thickness. With that said I feel confident that a few mm can make a big difference in all this.

One interesting article I found on devices known as "Thickness Gauges" talks about how different materials and their internal makeup/structure can affect sound/vibration propagation:

http://www.olympus-ims.com/en/ndt-theory/thickness-gage/factors/

http://www.olympus-ims.com/en/appli...ry-ultrasonics/introduction-thickness-gaging/

If your not aware of what these devices do, they use transducers to generate sound at various Freq and use that to measure the thickness of a material by calculating the time it takes for the sound to reflect back into the gauge. There is a decent explanation on the challenges involved in doing this due to the material makeup of different metals,plastics..etc.

So you dont have any idea of the real world practical effect the different metals /their propagation speed in this specific application. Please note I was specifically referring to the three versions with different metals and not the compliant material they are bonded to.

Just for your information I have been measuring and analysing vibration in a professional capacity in the aero and other industries for many years.

If the product is appropriately compliant I have no issue with its potential efficacy for isolating vibration.

 

[March Audio]

Not infinitely stiff, but can be made vastly superior to a simple metal pedestal - I would suggest that optimal mounting of speakers is not common.

Look up modal / fea analysis on youtube.

 

[March Audio]

So it seems they are saying that one of the main purposes of the Spike is to increase the Mass of the cabinet t.

How does the cabinets mass get increased? A spike coupling may affect how the object is constrained at that junction.

 

[fas42]

Here's a pic for clarity purposes of the factory spike, outrigger setup and Herbie cups deployed under my speakers as they sit today

Personally, if I had temporary control over your rig I would remove the whole stand assembly, leaving the bare cabinet. Then, I would place 4 largish balls of Blu Tack precisely under the extreme corners of the base - that is, directly coupling to the floor. To ensure an effective linking I would put my full weight and strength into pushing down the speakers, squashing out the goo as far as I could - it should feel like the speakers are glued to the floor.

This is the technique I've used all the way through my many system ventures - I've never decided at a later stage to reverse this situation ... .

 

[March Audio]

Personally, if I had temporary control over your rig I would remove the whole stand assembly, leaving the bare cabinet. Then, I would place 4 largish balls of Blu Tack precisely under the extreme corners of the base - that is, directly coupling to the floor. To ensure an effective linking I would put my full weight and strength into pushing down the speakers, squashing out the goo as far as I could - it should feel like the speakers are glued to the floor.

This is the technique I've used all the way through my many system ventures - I've never decided at a later stage to reverse this situation ... .

changing the height and bringing that woofer closer to the floor will change the speakers response far more than any mounting /fixing method.

 

[Don Hills]

... They have been sitting firmly in the same now deeply compressed spots on my carpet for years. ... The stands also sit in their own, now deep impressions firmly in the carpet.

This is one case in which spikes are better than casters or glides, though not for the reason you might think. They don't mark the carpet, thus reducing the noise from the spousal unit.

 

[fas42]

changing the height and bringing that woofer closer to the floor will change the speakers response far more than any mounting /fixing method.

It may alter some of the bass response, but I'm interested in 'tight' bass, not wooly sound - the gains in reduction of distortion from the speaker cabinet being constrained to a much greater degree far outweigh any alteration of the nominal response curve.

 

[Nightlord]

Not really. In everyday items it's called memory foam, the stuff when you squash it just slooowly reverts back to normal shape. With furniture foam you can buy the standard, just springy, varieties; or specify memory versions, for a bit more cost.

The technical term is viscoelastic, means exactly what it implies: springy but also viscous; the shape reverts back slowly, rather than as fast as possible. Sorbothane is the classic commercial brand that people think of.

The big advantage is that viscous means damping - the energy stored by any deflection is converted to heat, rather than decaying very slowly - continual bouncing is prevented. The suspension of a car is a perfect example; with worn out shock absorbers, dampers you can see the wheels doing a merry dance.

Well, what I am buying is from a company that specializes in feet for speakers, either you go for the cheaper way and pick in a weight range, or you weigh your speakers front & back (or every corner if unsymmetrical) and tell them the weights and they pick out the right feet for you. They're called Sonic Design and resides in Stockholm, Sweden. How they source the material and what it is, is of little concern to me. That it works - is.

 

[amirm]

So what is the right measurement for these things guys?

 

[Fitzcaraldo215]

So what is the right measurement for these things guys?

I think it would be in-room frequency response with/without footers as mike measured with impulsed test tones.

 

[Thomas savage]

I'm forever hearing subjective anecdotes about ' tighter bass' ' all boomyness has gone' ... that should show easily on a in room frequency response test..

 

[Deleted member 65]

I'm forever hearing subjective anecdotes about ' tighter bass' ' all boomyness has gone' ... that should show easily on a in room frequency response test..

So am I, here's another from me in the real life.

I bought my Evolution Acoustics MMMicroOne speakers (now in my second music room, why did they have to have three M's?) from darTZeel in Switzerland. Not happy at all from first listening, sounded wooly, not focused or detailed. Okey, they need time to settle in....... Three months later, settled in but did not perform as I'd expected them to.

What's a poor man to do?

Buy eight pieces of the Norwegian product Soundcare Spikes, did just that and the speakers transformed from disappointments to ... well musical appointments.

Then stored away, new speakers arrived, kid moved out, new room converted into second music room, MMM speakers got a new life ... all well ...

PS. Not sure on the topic relevance but my Norwegian Forest cat (16 yo female) decided to jump up and cuddle with me after the ... all well ... DS

 

[Fitzcaraldo215]

Did a naked, winged, flying placebo just pass through the room?

 

[Deleted member 65]

Did a naked, winged, flying placebo just pass through the room?

No, no, no but this just flew by - - >